<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-08-13</periodOfReport>
    <issuer>
        <issuerCik>0000076334</issuerCik>
        <issuerName>PARKER HANNIFIN CORP</issuerName>
        <issuerTradingSymbol>PH</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001021749</rptOwnerCik>
            <rptOwnerName>GAREY DANIEL T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>PARKER-HANNIFIN CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>6035 PARKLAND BOULEVARD</rptOwnerStreet2>
            <rptOwnerCity>CLEVELAND</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44124-4141</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>VP - Human Resources</officerTitle></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Option to Buy</value></securityTitle><conversionOrExercisePrice><value>47.29</value></conversionOrExercisePrice><transactionDate><value>2003-08-13</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>12775</value></transactionShares><transactionPricePerShare><footnoteId id="F2"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F1"/></exerciseDate><expirationDate><value>2013-08-12</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>12775</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>12775</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">The option vests in two equal installments on 8/13/04 and 8/13/05.</footnote><footnote id="F2">Granted under the Corporation's Non-Employee Directors Stock Option Plan in a transaction exempt under Rule 16b-3.</footnote></footnotes><remarks/><ownerSignature><signatureName>Thomas L. Meyer, Attorney-in-Fact</signatureName><signatureDate>2003-08-15</signatureDate></ownerSignature></ownershipDocument>

